TC4钛合金电子束表面造型形貌及近表面组织特征

Topography and near-surface microstructure of TC4 alloy treated by electron beam surfi-sculpt TM

对采用电子束表面微造型技术加工的TC4钛合金非光滑表面进行了研究。研究发现,通过该技术加工的非光滑表面具有截面为波浪形的沟槽,而且通过调节加工参数,可制备不同尺寸特征的沟槽。加工的沟槽沟脊处存在连续分布的鱼鳞状形貌,而沟谷处存在连续分布的倒V形条纹,鱼鳞形貌大小和V形条纹的间距均与加工参数有关。加工后的近表面从上至下由熔化区、热影响区和母材组成,熔化区由马氏体组成,热影响区位于熔化区和母材之间,其微观组织与母材也存在很大差异。熔化区和热影响区的显微硬度均要高于母材,而且在熔化区和热影响区的界面处存在显微硬度的最大值。电子束表面微造型的减阻效果可以达到15%以上。

The topography and near-surface microstructure of TC4 Ti alloy treated by electron beam surfi-sculpt TM were studied.It was found that the non-smooth surface of TC4 alloy exhibited wave shaped grooves with sizes able to be customized by adjusting processing parameters.The ridge of the groove displayed continuous scales while the valley presented inverted V shape stripes.The dimensions of the ridge and valley are also related to and could be controlled by processing parameters.The near-surface region of TC4 alloy treated by electron beam surfi-sculpt TMis occupied by the fusion zone,heat affected zone and base metal from the top down to the underlying bulk alloy.The microstructure of the fusion zone is characterized by martensite phase,while the heat affected zone sandwiched between the fusion zone and the base metal also presented microstructures different from that of the base metal.The fusion zone and heat affected zone possesses higher micro-hardness compared with the base metal,with the maximum value appearing at the interface between the fusion zone and the heat affected zone.A fluid-drag reduction efficiency over 15%is achieved on TC4 alloys treated by electron beam surfi-sculpt TM.